Re: [PATCH] serial: sh-sci: Fix receive on SCIFA/SCIFB variants with DMA

[Wolfram Sang]

On Tue, Oct 09, 2018 at 07:41:58PM +0200, Geert Uytterhoeven wrote:
> On SCIFA and SCIFB serial ports with DMA support (i.e. some ports on
> R-Car Gen2 and RZ/G1 SoCs), receive DMA operations are submitted before
> the DMA channel pointer is initialized.  Hence this fails, and the
> driver tries to fall back to PIO.  However, at this early phase in the
> initialization sequence, fallback to PIO does not work, leading to a
> serial port that cannot receive any data.
> 
> Fix this by calling sci_submit_rx() after initialization of the DMA
> channel pointer.
> 
> Reported-by: Jinzai Solution and RVC Test Teams via Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>

Brainstorming: keep Shimoda-san's address as is and mention the test
teams in the commit message?

> Fixes: 2c4ee23530ffc022 ("serial: sh-sci: Postpone DMA release when falling back to PIO")
> Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>

Reviewed-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>

> ---
> Reported on r8a7790/lager using SCIFA1 on Debug Serial 1.

I hope to test this on Lager this weekend. I am quite sure it will work
now, but then we have this formally checked, too.

> Tested on r8a7791/koelsch using SCIFA3 on EXIO-B.

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